A parking assistance device that is mounted on a vehicle in order for a parking assistance is known. The parking assistance device, for example, detects an obstacle such as another parked vehicle and determines a route to a target parking position while avoiding the obstacle. The parking assistance device assists the parking based on the route.
In a case of determining the route, for example, there is a method (hereinafter, referred to as a “method 1 in the related art”) in which shapes of the obstacles at both sides of the target parking position are continuously detected even during the parking assistance and the route is changed, if necessary. According to this method, it is possible to improve accuracy of the route.
In addition, there is also a method (hereinafter, referred to as a “method 2 in the related art”) in which a side surface of the obstacle in the target parking position side (hereinafter, referred to as an “inner side surface”) is detected using ultrasonic sonar, and further, a position of the inner side surface of the obstacle is determined using an image in which the inner side surface is in the vicinity of the center among the images that include the inner side surfaces continuously captured by a camera. According to this method, it is possible to determine the target parking position with high accuracy before the parking assistance.
Japanese Patent No. 5469663 and JP 2010-267115A are examples of the related arts.
However, in the method 1 in the related art, the route is changed even after the vehicle enters the target parking position during the parking assistance. Therefore, there is a problem in that a correct target parking position is delayed to be recognized, and thus, it takes a time in parking the vehicle due to the forward and backward turnings.
In addition, in the method 2 in the related art, in some cases, there is no image in which the inner side surface is captured in the vicinity of the center depending on a sampling rate of imaging or a speed of the host vehicle, and thus, there is a problem in that an error of the target parking position increases.